Index oversize text for search.

SignalServiceKit/src/Messages/Attachments/TSAttachmentStream.h

@@ -58,6 +58,9 @@ NS_ASSUME_NONNULL_BEGIN
 - (BOOL)writeData:(NSData *)data error:(NSError **)error;
 - (BOOL)writeDataSource:(DataSource *)dataSource;
 
+- (BOOL)isOversizeText;
+- (nullable NSString *)readOversizeText;
+
 + (void)deleteAttachments;
 + (NSString *)attachmentsFolder;
 

SignalServiceKit/src/Messages/Attachments/TSAttachmentStream.m

@@ -672,6 +672,27 @@ NS_ASSUME_NONNULL_BEGIN
     return [OWSBackupFragment fetchObjectWithUniqueID:self.lazyRestoreFragmentId];
 }
 
+- (BOOL)isOversizeText
+{
+    return [self.contentType isEqualToString:OWSMimeTypeOversizeTextMessage];
+}
+
+- (nullable NSString *)readOversizeText
+{
+    if (!self.isOversizeText) {
+        OWSFail(@"%@ oversize text attachment has unexpected content type.", self.logTag);
+        return nil;
+    }
+    NSError *error;
+    NSData *_Nullable data = [self readDataFromFileWithError:&error];
+    if (error || !data) {
+        OWSFail(@"%@ could not read oversize text attachment: %@.", self.logTag, error);
+        return nil;
+    }
+    NSString *_Nullable string = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
+    return string;
+}
+
 #pragma mark - Update With... Methods
 
 - (void)markForLazyRestoreWithFragment:(OWSBackupFragment *)lazyRestoreFragment

SignalServiceKit/src/Storage/FullTextSearchFinder.swift

@@ -194,9 +194,48 @@ public class FullTextSearchFinder: NSObject {
     }
 
     private static let messageIndexer: SearchIndexer<TSMessage> = SearchIndexer { (message: TSMessage) in
-        return message.body ?? ""
+        if let body = message.body, body.count > 0 {
+            return body
+        }
+        if let oversizeText = oversizeText(forMessage: message) {
+            return oversizeText
+        }
+        return ""
     }
 
+    private static func oversizeText(forMessage message: TSMessage) -> String? {
+        guard message.hasAttachments() else {
+            return nil
+        }
+        guard let dbConnection = dbConnection else {
+            owsFail("Could not load attachment for search indexing.")
+            return nil
+        }
+        var oversizeText: String?
+        dbConnection.read({ (transaction) in
+            guard let attachment = message.attachment(with: transaction) else {
+                owsFail("Could not load attachment for search indexing.")
+                return
+            }
+            guard let attachmentStream = attachment as? TSAttachmentStream else {
+                return
+            }
+            guard attachmentStream.isOversizeText() else {
+                return
+            }
+            Logger.verbose("attachmentStream: \(attachmentStream.contentType)")
+            Logger.flush()
+            guard let text = attachmentStream.readOversizeText() else {
+                owsFail("Could not load oversize text attachment")
+                return
+            }
+            oversizeText = text
+        })
+        return oversizeText
+    }
+
+    private static var dbConnection: YapDatabaseConnection?
+
     private class func indexContent(object: Any) -> String? {
         if let groupThread = object as? TSGroupThread {
             return self.groupThreadIndexer.index(groupThread)
@@ -236,6 +275,12 @@ public class FullTextSearchFinder: NSObject {
     }
 
     private class var dbExtensionConfig: YapDatabaseFullTextSearch {
+        SwiftAssertIsOnMainThread(#function)
+
+        if dbConnection == nil {
+            dbConnection = OWSPrimaryStorage.shared().newDatabaseConnection()
+        }
+
         let contentColumnName = "content"
 
         let handler = YapDatabaseFullTextSearchHandler.withObjectBlock { (dict: NSMutableDictionary, _: String, _: String, object: Any) in